You did try to just burn it, not open it? Just that you mentioned WinRar, and the only thing you could have done with that is try to open the image and see the files inside, which won't work because none of the standard Windows tools will "open" the Rhapsody ISO and display its files, but they will burn it without opening it.

You tried booting VMware from the Rhapsody boot floppies and using this CD to install, and it didn't work? (just checking, because it may look like a blank disc in Windows because Rhapsody discs use a special filesystem that you won't be able to see in Windows)

Vista Ultimate R2 is perfectly right. The Rhapsody disc probably uses an UFS file system which Windows doesn't have a clue about and thus, the CD will appear blank. Open the image with ISOBuster or something like that and look what it says. Anyway, you should try to install Rhapsody from the CD/ISO because that's about the only safe way to tell if the ISO is okay or not.

I just checked my Rhapsody DR2 x86 image that I used to install the system (so I know it works), and even Mac OS X says it doesn't have any recognized file systems. (But it recognizes my Mac OS X Server 1.0 CD just fine)

The CD is not bootable - you must boot using the two boot floppies. Just download them, and then point VMware at the first image (I don't know what you need to use to make actual floppies, but VMware will boot from the images, if you tell it to look for all types of floppy image rather than just the types that it wants to look for by default).